In the Pb–Sn system, calculate the alloy composition at which the fraction of total 􀀀 is 2½ times the fraction of the phase at 182°C.

 

For soldering with Pb–Sn alloys, at least 85% of the eutectic mixture is preferred in the microstructure. Determine the composition limits of tin that will satisfy this condition.

 

Calculate the fraction of proeutectoid ferrite, eutectoid ferrite and total ferrite in a 0.2% C steel.

 

The potassium–sodium binary phase diagram has the following invariant reactions: cooling at 6.9°C, + L Na2K wt.% Na 99 47 54 cooling at –12.6°C, L 􀀀 + Na2K wt.% Na 23 3 54 (i) Give the name of each of the above reactions. (ii) Make an approximate sketch of the phase diagram. (iii) Find the fraction of Na2K in a 33 wt.% Na alloy at –12.5°C.

 

In the Ti–Ti2Co system, liquid of 27 wt.% Co, of 17 wt.% Co and Ti2Co of 38 wt.% Co are in equilibrium at 1020°C. At 685°C, of 8 wt.% Co, 􀀀 of 1 wt.% Co and Ti2Co are in equilibrium. Pure Ti melts at 1670°C and also undergoes a crystal structure change from (BCC) to 􀀀 (HCP) on cooling through 882°C. Ti2Co is stable up to 1058°C.

 

The data on the gold–lead phase diagram are given below. Melting point of Au = 1063°C, Melting point of lead = 327°C. At 434°C, Au, liquid of 43 at.% Pb and Au2Pb are in equilibrium. At 253°C, Au2Pb, liquid of 74 at.% Pb and AuPb2 are in equilibrium. At 222°C, AuPb2, AuPb3 and liquid of 82 at.% Pb are in equilibrium. At 212°C, AuPb3, Pb and liquid of 84 at.% Pb are in equilibrium. Draw the phase diagram on a graph paper using a suitable scale. Write down the invariant reactions, giving the name of each.

 

In the Fe–Fe2Nb system, at 1373°C, of 3% Nb, liquid of 12% Nb and of 27% Nb are in equilibrium. At 1210°C, of 1% Nb, of 1.5% Nb and of 27% Nb are in equilibrium. At 961°C, of 0.4% Nb, 􀀀 of 0.7% Nb and of 27% Nb are in equilibrium. All compositions are in atomic%. The melting point of Fe is 1535°C and of Fe2Nb (33.3 at.% Nb) is 1627°C. The phase is stable over a composition range of 27 to 33.3 at.% Nb, (i) Draw an approximate phase diagram for this system. (ii) Write down the invariant reactions in the system, giving their names. (iii) What is the fraction of 􀀀 in an alloy with 10% Nb at 960°C?

 

The Al–Si phase diagram is of the simple eutectic type. At 577°C, solid Al with 1.5% Si dissolved in it, solid Si and liquid of 12.5% Si are in equilibrium. An aluminium wire is welded to a silicon substrate. Just below the weld inside the substrate, the microstructure shows 2% of a eutectic-like mixture. What is the composition at this location?

In the Ge–P system, a compound GeP exists. At 725°C, Ge, GeP and liquid of 62 at.% P are in three-phase equilibrium. At 577°C, GeP, P and liquid of 94.5 at.% P are in equilibrium. The melting points of Ge and P are 937 and 593°C respectively. Draw an approximate phase diagram of this system. Write down the invariant reactions, giving their names.

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GATE 2022 Job at IOCL

Hello GATE 2022 Rankers.

Here is good opportunity for those who has cleared GATE 2022 to get good job in one of the finest company IOCL.

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Eligible branches are :

a. Chemical Engineering 

b. Civil Engineering 

c. Computer Sc and Engineering 

d. Electrical Engineering

e. Instrumentation Engineering

f. Mechanical Engineering 

g. Metallurgical Engineering

Other conditions:

Candidates must have qualified in the GATE 2022 examination from one of the following disciplines in order to be eligible to apply for the advertised posts: i. Chemical Engineering (GATE 2022 code: CH) ii. Civil Engineering (GATE 2022 code: CE) iii. Computer Sc & Engineering (GATE 2022 code: CS) iv. Electrical Engineering (GATE 2022 code: EE) v. Instrumentation Engineering (GATE 2022 code: IN) vi. Mechanical Engineering (GATE 2022 code: ME) vii. Metallurgical Engineering (GATE 2022 code: MT) b. A candidate can apply in IOCL only in any one of the aforesaid disciplines. However, in order to apply, the candidate must have qualified GATE 2022 examination in the said discipline and also done his/her BE/B.Tech from the same discipline [including corresponding engineering disciplines mentioned in para 1.3] discipline in GATE 2022 For example: In case a candidate has qualified in GATE 2022 from 2 papers – say Electrical Engg and Instrumentation Engg – and has done BE/B.Tech in Instrumentation Engg, then the candidate can apply only in Instrumentation Engg and not in Electrical Engg for this recruitment. c. Qualifying in GATE 2022 from disciplines other than 07 (Seven) disciplines mentioned above shall not be accepted towards eligibility for the advertised post. d. GATE marks of previous years (GATE 2021 or before) shall also not be accepted.

r/R ratio shortcut BCC (B) and FCC (F)

This is the video which will show the trick to remember the r/R ratio of tetrahedral and octahedral voids in BCC and FCC.